curl --request GET \
  --url https://drb.coinbase.com/api/v2/private/cancel \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": 4214,
  "jsonrpc": "2.0",
  "method": "private/cancel",
  "params": {
    "order_id": "ETH-SLIS-12"
  }
}
'

{
  "id": 4214,
  "jsonrpc": "2.0",
  "result": {
    "amount": 5,
    "api": false,
    "creation_timestamp": 1550575961291,
    "direction": "sell",
    "instrument_name": "ETH-PERPETUAL",
    "is_liquidation": false,
    "is_rebalance": false,
    "label": "",
    "last_update_timestamp": 1550575961291,
    "max_show": 5,
    "order_id": "ETH-SLIS-12",
    "order_state": "untriggered",
    "order_type": "stop_market",
    "post_only": false,
    "price": "market_price",
    "reduce_only": false,
    "time_in_force": "good_til_cancelled",
    "trigger": "index_price",
    "trigger_price": 144.73,
    "triggered": false
  }
}